We originally had thirty-six (36) animals in this project, and described two sets of experiments, one which was to place membranes in created mandibular chronic defects, keep the membranes in position for a year, regenerate bone, and place implants in regenerated bone to compare these with implants in bone which had not been regenerated. We placed the last of these implants on January 23, 1997. We allow three months for healing, and then prostheses are placed. At the present time, we have five prostheses placed, and anticipate having all the prostheses placed by the summer of 1997, which will allow exit dates during the summer of 1998, which will keep us on schedule. However, we have only examined radiographic data to this point. In addition to the protocol of implant placement in regenerated bone, we have a second protocol which examines growth factors and cytokines released at various time intervals after membrane placement. We are on schedule with this, and will have exited all the animals in early 1997. These data are constantly being examined by Dr. Offenbacher, but we are reluctant to make any comments at this time, as the data are incomplete. We can, however, comment on the fact that using membrane technology, we are very close to our predicted value of 20% early exposure and removal. The significance of being able to regenerate bone has important scientific and clinical implications, both in the field of dentistry and in the approach to bone growth in other areas of the body. Certainly, to be able to accelerate the time that bone is grown is a very significant area of research at present, and will lead to enhancement of the dental implant field. Currently, we are also working with spinal surgeons and cranial-facial surgeons in a future protocol to regenerate spinal and cranial-facial defects. Other areas which have high clinical importance would be regeneration of mandibular bone where there are carcinomas of the mandible which require resection. P51RR00165-36 1/1/1996-12/31/1996 Yerkes Regional Primate Research Center